STS-115 was a Space Shuttle mission to the International Space Station (ISS) flown by Space Shuttle Atlantis. The mission launched on September 9, 2006, and was the fourteenth shuttle mission to visit the ISS. The primary objective of the mission was to install the P3/P4 (P-three/P-four) Truss, which would provide additional structural support and a mounting point for solar arrays, radiators, and other equipment on the ISS. The mission also included the delivery of supplies and equipment to the ISS and the installation of a spare cooling pump on the station.